I think it almost entirely depends on you and your level. I'm a singer also, an alto, but I'm not applying with voice but I also think voices take time to mature. like you may want to ask yourself when you started, how much time you put in, how much repertoire you perform and at what level etc. sort of like what other instrumentalists will be doing.
however, I do know someone who was a soprano singer and she went straight into conservatoire (Wales) without a gap year. same thing which a friend did as a baritone (birmingham). one started her singing journey at around 12, and the other at around 10 however, this means nothing in the music world as people learn at completely different paces.
If I were you, I may apply this year, see how it goes and if I think I could do better next year, then I'd reapply again next year. there is no shame trying the application process. In fact, it may help you if you want to take a gap year and apply again as you'll have experience and more knowledge on which conservatories you'd like to study at and aspire to get into.
Whilst I'm not applying for voice, I am a composer, I took a gap year (last year) and it has done wonders for my musical language and development and it is clearly showing as last year, I had to be painfully honest with myself and say that my portfolio would get me nowhere! however, this year, my application has been highly successful and I have far more options of study than I would ever have had last year!
So in short, this is your decision. others may have their input but you have to know yourself and what you want for the next 4/5 years of your life!
I wish you all the best!